IS 4511 (Part 5) :2005 ISO 7781:2001 ( Reaffirmed 2002 ) mdkvnm m-'qmw m (m~)r `WJ'15 (v METHOD PART 5 3T?m) Indian Standard OF TEST FOR STYRENE-BUTADIENE RUBBER (SBR), LATICES OF SOAP AND ORGANIC-ACID CONTENT DETERMINATION (Second Revision ) ICS 83.140.40 061S 2005 BUREAU MANAK BHAVAN, OF INDIAN STANDARDS SHAH 110002 ZAFAR MARG 9 BAHADUR NEW DELHI April 2005 Price Group 3 Rubber and Rubber Products Sectional Committee, PCD 13 NATIONAL FOREWORD This Indian Standard (Part 5) (Second Revision) which is identical with ISO 7781 :2001 `Styrenebutadiene rubber, raw -- Determination of soap and organic-acid content' issued by the International Organization for Standardization (ISO) was adopted by the Bureau of Indian Standards on the recommendations of the Rubber and Rubber Products Sectional Committee and approval of the Petroleum, Coal and Related Products Division Council. The text of ISO Standard has been proposed to be approved as suitable for publication as an Indian Standard without deviations. Certain conventions are, however, not identical to those used in Indian Standards. Attention is particularly drawn to the following: a) Wherever the words `International be read as `Indian Standard'. Standard' appear referring to this standard, they should b) Comma (,) has been used as a decimal marker while in Indian Standards, the current practice is to use a point (.) as the decimal marker. The Technical Committee responsible for the preparation of this standard has reviewed the provisions of the following International Standards and has decided that they are acceptable for use in conjunction with this standard: International $tandard Title ISO 385-1:1984 ISO 648:1977 ISO 1042:1998 Laboratory Laboratory Laboratory glassware -- Burettes -- Part 1: General requirements glassware -- One-mark glassware -- One-mark pipettes volumetric flasks and further preparative 1s0 1795:2000 ISO 4799:1978 Rubber, raw natural and raw synthetic -- Sampling procedures Laboratory glassware -- Condensers In reporting the results of a test or analysis made in accordance with this standard, if the final value, observed or calculated, is to be rounded off, it shall be done in accordance with IS 2:1960 `Rules for rounding off numerical values (revised)'. IS 4511 ISO 7781 (Part 5) :2005 :2001 Indian Standard METHOD OF TEST FOR STYRENE-BUTADIENE RUBBER (SBR), LATICES PART 5 DETERMINATION ( OF SOAP AND ORGANIC-ACID CONTENT Second Revision) WARNING -- Persons using this International Standard should be familiar with normal laboratory practice. This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user to establish appropriate safety and health practices and to ensure compliance with any national regulatory conditions. 1 Scope This International Standard specifies methods for the determination of the soap and organic-acid content of raw styrene-butadiene rubber (SBR). Method A is suitable for non-oil-extended styrene-butadiene rubbers. Method B is applicable to oil-extended styrene-butadiene rubbers. The methods depend on the extraction of the organic acids and soaps from the rubber by means of a specified solvent. In practice, therefore, it is convenient to determine both organic-acid and soap contents on separate portions of the same solvent extract. Since the soaps and organic acids present in the rubber are not single chemical compounds, the method gives only an approximate value for the soap and organic-acid content. `. 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 385-1:1984, 1S0 648:1977, ISO 1042:1998, ISO 1795:2000, ISO 4799:1978, Laboratory Laboratory Laboratory glassware glassware glassware -- Burettes -- Part 1: General requirements -- One-mark pipettes -- One-mark volumetric flasks procedures Rubber, raw natural and raw synthetic -- Sampling and further preparative Laboratory glassware -- Condensers 3 Principle A weighed test portion of the rubber, in the form of thin strips, is extracted by ethanol-toluene azeotrope, or, for alum-coagulated rubber, ethanol-toluene-water mixture. After making up to a standard volume, an aliquot portion of the extract is withdrawn and titrated with standard acid for the determination of soap and with standard alkali for the determination of organic acid. IS ISO 4511 7781 (Part 5) : 2005 :2001 4 Reagents During the analysis, use only reagents of recognized analytical grade and only distilled water or water of equivalent " purity. Use commercially available analytical-grade buffer solutions of known pH or, in the absence of commercial buffer solutions, prepare the solutions required (4.6, 4.7 and 4.8). 4.4 Ethanol-toluene azeotrope (ETA). Mix 7 volumes of absolute ethanol with 3 volumes of toluene. Alternatively, mix 7 volumes of commercial-grade ethanol with 3 volumes of toluene, and boil the mixture with anhydrous calcium oxide (quicklime) under reflux for 4 h. Cool to room temperature and decant through No. 42 filter paper. 4.2 Ethanol-toluene-water mixture. Mix 95 cm3 of ETA (4.1) and 5 cm3 of water. 4.3 4.4 Sodium hydroxide solution, c(NaOH) = 0,1 mol/dm3, accurately standardized. Thymol blue indicator. 0,06 g of thymol blue in 6,45 cm3 of 0,02 mol/dm3 sodium hydroxide solution and dilute to 50 cm3 with Dissolve water. 4.5 4.6 Hydrochloric acid, c(HCI) = 0,05 mol/dm3, accurately standardized. Buffer solution of nominal pH 7. Dissolve 3,40 g of potassium dihydrogen phosphate (KH2P04) and 3,55 g of disodium hydrogen phosphate (Na2ilP04) in water and makeupto1000 cm3 in a volumetric flask. The pH of this solution is 6,87 at 23 "C. Store the soiution in a glass or polyethylene 4.7 Buffer solution of nominal pH 4. in water and make up to 1000 cm3 in a vessei that is resistant to chemicals. Dissolve 10,21 g of potassium hydrogen phthalate (HOOCC6H4COOK) volumetric flask. The pH of this soiution is 4,00 at 23 "C. Store the solution in a glass or polyethylene 4.8 Buffer soiution of nominai pH 9. vessei that is resistant to chemicals. Dissoive 3,814" g of sodium tetraborate decahydrate (Na2B407.10H20) in water and make up to 1000 cm3 in a volumetric flask. The pH of this solution, when freshly prepared, is 9,20 at 23 "C. Store the solution in a giass or polyethylene vessel that is resistant to chemicals dioxide trap. Repiace the solution after 1 month. and fitted with a soda lime carbon 5 5.4 5.2 5.3 5.4 Apparatus Balance, accurate to 1 mg. Hotplate. Wide-mouthed Volumetric conical flask, capacity 400 cm3 to 500 cm3. flask, capacity 250 cm3, complying with the requirements of ISO 1042. 2 IS 4511 ISO 7781 (Part 51: 2005 :2001 5.5 5.6 NOTE 5.7 5.8 Reflux condenser, complying with the requirements of ISO 4799. Conical flask, capacity 250 cm3. Alternatively, a Soxhlet extractor maybe used instead of a refiux condenser and a conical flask. Burette, Pipette, capacity 25 cm3, complying with the requirements capacity titrator 100 cm3, complying with the requirements or pH-meter, of ISO 385-1. of ISO 648. and glass electrode, accurate to within 10mV 5.9 Automatic or 0,1 pH-units. 5.10 Magnetic including a calomel electrode stirrer, with a polytetrafluoroethylene-coated stirrer bar. 6 Sampling and sample preparation largerthan 2-g to the Sheet out 2 g to 6 g of rubber, selected and prepared in accordance with ISO 1795. Cut into pieces no 2 mm x 2 mm or st;ps no longer than 10 mm or" wider than 5 mm. Weigh a test portion of approximately nearest 0,001 g. 7 7,1 Procedure Preparation of the test solution Place a circular filter paper in the bottom of the wide-mouthed conical flask (5.3) and add 100 cm3 of ETA extraction solvent (4. 1) for all rubbers except alum-coagulated rubbers. For alum-coagulated rubbers, use ethanoltoluene-water mixture (4.2). . Introduce the strips of rubber separately into the flask, swirling after each addition so that the strips are thoroughly wetted with solvent and sticking is minimized. Fit the reflux condenser (5.5) to the flask and boil the solvent very gently under reflux for 1 h. Transfer the extract to the volumetric flask (5,4), and treat the rubber with a second 100 cm3 portion of extraction solvent under reflux for 1 h. Add this extract also to the volumetric flask. Rinse the strips with three successive 10 cm3 portions of extraction solvent, add these washings to the volumetric flask and, after cooling to room temperature, adjust the final volume to 250 cm3 with appropriate extraction solvent. NOTE Alternatively, the weighed strips of sample may be wrapped in filter paper and placed in a Soxhlet extractor (see note to 5.6) and extracted with ETA (4.1) or ethanol-toluene-water mixture (4.2) under reflux for a minimum of 4 h. 7.2 7.2.1 Method A (for non-oil-extended SBR) Procedure for determination of soap content After thorough mixing, pipette 100 cm3 of the diluted extract into the 250 cm3 conical flask (5.6), add six drops of thymol blue indicator (4.4) and titrate the solution with hydrochloric acid solution (4.5) to the first coiour change (Vl). Carry out a blank titration on 100 cm3 of extraction solvent taken from the same stock as was used for the test portion and using the same indicator as was used for titration of the test portion (V2). 3 IS 1S0 4511 7781 (Part 5) :2005 :2001 7.2.2 Procedure for determination of organic-acid content solution (4.3), again using thymol Proceed exactly as in 7.2.1, but titrate the aliquot portion with sodium hydroxide blue indicator (4.4) ( V3). Carry out a blank titration on 100 cms of extraction solvent using the same method (V4). 7.3 7.3.1 Method B (for oil-extended for determination SBR) of soap content shown by Procedure Turn on the autotitrator or pH-meter (5.9), and allow the electronic circuit to stabilize. The temperature the temperature compensator indicator shall be same as the temperature of the test solution. Calibrate the autotitrator or pH-meter using nominally pH 7 buffer solution (4.6) and pH 4 buffer solution (4.7). into a 250 cm3 beaker containing a stirrer bar, then place the beaker on the Pipette 100 cms of the test solution magnetic stirrer (5. 10). Insert a glass electrode and a calomel electrode into the test solution in the beaker. While stirring, titrate the test solution with hydrochloric acid solution (4.5) to pH 4,8, slowing the titration rate near the equivalence point. Record the volume of hydrochloric acid solution used at the equivalence point ( VI ). Carry out a blank titration on 100 cms of extraction solvent using the same method (V2). 7.3.2 Procedure for determination of organic-acid content pH 7 buffer solution (4.6) and pH 9 buffer solution (4.8). Calibrate the autotitrator or pH-rneter using nominally Proceed exactly as in 7.3.1, but titrate the aliquot portion with sodium hydroxide solution (4.3) to pH 11,5, again slowing the titration rate near the equivalence point. Record the volume of sodium hydroxide solution used at the equivalence point (V3). Carry out a blank titration on 100 cm3 of extraction solvent using the same method (V4). 8 8.1 Expression Calculate of results the soap content using the equation v2)Xcl XK~ 0,2!ix(V1},)~ = m where w~ V1 V2 is the soap content, as a percentage by mass; acid solution used to titrate the rubber extract acid solution used to titrate the blank; is the volume, in cubic centimetres,, of hydrochloric is the volume, in cubic centimetres, of hydrochloric c1 m is the actual concentration, in mol/dm3, of the hydrochloric acid solution (4.5) is the mass, in grams, of the test portion; is the appropriate factor selected from the following: as sodium stearate, as sodium rosinate, KS 306 when the soap is to be calculated 368 when the soap is to be calculated 4 IS ISO 4511 7781 (Part 5) :2005 :2001 337 when the soap is to be calculated as a 50:50 mixture of sodium stearate and sodium rosinate, 322 when the soap is to be calculated as potassium stearate, 384 when the soap is to be calculated 353 when the soap is to be calculated as potassium rosinate, stearate and potassium rosinate, as a 50:50 mixture of potassium 345 when the soa~ is to be calculated as a 50:50 mixture of sodium stearate and potassium sodium rosinate and potassium stearate, rosinate or of NOTE Since the soaps present in the rubber are not single chemical compounds, the value assigned to Ks gives only an approximate value for the soap content. A test for rosin is given in annex A. 8.2 Calculate the organic-acid 0,25X(~3-~4)XC2x~0 ~. content using the equation m where W. is the organic-acid content, expressed as a percentage by mass; V3 is the volume, in cubic centimetres, of sodium hydroxide solution used to titrate the test solution; V4 is the volume, in cubic centimetres, c2 m of sodium hydroxide solution used to titrate the blank; is the actual concentration, in mol/dm3, of the sodium hydroxide solution (4.3); is the mass, in grams, of the test portion; is the appropriate factor selected from the following: as stearic acid, as rosin acid, as a 50:50 mixture of stearic acid and rosin acid. K. 284 when the acid is to be calculated 346 when the acid is to be calculated 315 when the acid is to be calculated Since the organic acids present in the rubber are not single chemical compounds, the value assigned to K. gives NOTE only an approximate value-for the organic acid content. A test for rosin is given in annex A. 9 Test report information: of the sample; The test report shall include the following a) b) c) d) e) f) all details required for the identification a reference to this International the soap and/or organic-acid the method used (A or B); Standard; content and the value of K. used; details of any deviation from this International Standard; the date of the test. 5 IS 4511 (Part 5) :2005 ISO 7781 :2001 Annex A (informative) Test for rosin A.1 Reagents A.1.1 A.1.2 Acetic anhydride. Sulfuric acid solution. = 1,84 g/cm3) to 35 g of water and mix well. = 0,0002 mol/dm3. Carefully add 65 g of sulfuric acid (n. A.I.3 Potassium permanganate solution, c(KMn04) A.2 Procedure Mix a small amount of sample with about 3 cm3 of acetic anhydride (Al .1). Add 2 drops of sulfuric acid (Al .2). The reaction is positive for rosin if a temporaty violet colour appears which, at the moment of its maximum intensity, is stronger than the colour of the potassium permanganate solution. " . 6 Bureau of Indian Standards BIS is a statutory institution established under the Bureau of Indian Standards Act, 1986 to promote certification of ~ harmonious development of the activities goods and attending to connected matters of standardization, in the country. marking and quality Copyright BIS has the copyright of all its publications. No part of these publications may be reproduced in any form without the prior permission in writing of BIS. This does not preclude the free use, in the course of implementing designations. Review the standard, relating of necessary to copyright details, such as symbols to the Director and sizes, type or grade BIS. Enquiries be addressed (Publications), of Indian Standards as the need arises on the basis of comments. 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